At the moment 32bit cudaminer 2013-11-20. Win Vista x64, 331.82 driver.
Tried different versions of cudaminer, different versions of drivers. Situation is the same.
Last week had 9500GT. With the same cudaminer and driver version, using config -l F4x4 had stable 9.5kh/s and no difference in speed with every launch of cudaminer. But autoconfig was not working right too. Seems strange, that the same family cards are so different in results...(in stability, not the max speed, because 8800/9800GT must be more than 2x faster than 9500GT).